Map Design: An On-the-Road Evaluation of
the Time to Read Electronic Navigation Displays

Christopher Nowakowski and Paul Green

June, 1998

This report covers the third of four experiments examining the time to read electronic maps while driving. Three factors were varied: (1) the number of streets displayed (12 street and 24 street maps), (2) the street label text size (10, 12, and 14 point), and (3) the time of day (day vs. night driving). Sixteen drivers (ages 18-30 and >65, both men and women) drove a test vehicle on public roads. Subjects were given three tasks while driving: (1) find the name of the street being driven, (2) find the name of a cross street ahead, and (3) find the location of a particular street on the map.

The largest effect was age which increased task response times by 40 to 80%. Each additional labeled street increased the response time by 7 to 140 ms depending on the task (up to 30%). Using 14 point reduced response time by 200 ms (up to 10%).

Subjective ratings by the drivers revealed uneasiness about their ability to drive safely when the task required more than 5 seconds to complete. To avoid this discomfort, using 14 point text and no more than 12 labeled streets is recommended.

Further, average response times from on-the-road were within 15% of the mean for the same task in a previous simulator experiment. The pattern of results (factors significant, their relative impact) were also similar, validating the simulator results.

Graphical Abstract (.pdf) | UMTRI-98-4 Full Report (.pdf)


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